Bacon, who has been living in the US, told Radio 4’s Broadcasting House that he had visited the gym twice a day in Los Angeles.

But the ex-Blue Peter presenter said he came close to death during the early part of his stay in the London hospital because of the still-mystery illness.

He told how he began feeling unwell during the flight, saying: “I started to feel very, very cold and slightly hallucinogenic…

“I felt like I was sitting in a field in winter and I was rocking back and forth. I was in such a state that when we landed after 10 hours that they had to get me off the plane in a wheelchair.”

Cleared for take off. Gone within the hour. I don’t know whether I see this as the bed I nearly died in or the bed that saved my life. Either way. I won’t miss it. But I will miss the 50 staff of Lewisham Hospital who definitely saved my life. Every. Single. One. Of. Them. pic.twitter.com/bOslPowxN4

But Bacon said: “This is where being in good shape worked against me. I think because I knew I had worked hard this year I thought, ‘I’ll be alright’ so I didn’t go straight to A&E which was a mistake.”

He said: “I was short of breath and what I should have done, and what I would urge anyone to do if ever short of breath through reasons they can’t ascertain, is you go straight to A&E.

“The next morning I went to A&E and even then I didn’t treat it very urgently. I just did a walk-in.”

He said during the first two nights in hospital “the infection was winning and my lungs were losing” and he has since found out he came “quite close to death” during this time.

“I have had a couple of moments of feeling slightly haunted by it,” he said.

Bacon said doctors will “never know” what he was struck by but added: “I’m fixed, it’s gone.”

He told the Radio 4 show: “I must have been injected 250 times in the last two weeks… because they didn’t know what it was.”

He added it was “the most shocking moment of my life”.

Bacon thought he would have one night in hospital but the consultant told him: “‘I need to put you into an induced coma so that we can control your breathing and if I don’t do that you’re probably going to die.’

“To start with it was profoundly shocking and then I was immediately at peace with it because he’d taken the decision away…